Assertion (A): Mixture of liquid air and air cannot be considered as pure substance.
Reason (R): Proportions of oxygen and nitrogen differ in liquid and gaseous states in equilibrium.
a) Both A and R are individually true and R is the correct explanation of A
b) Both A and R are individually true but R is not the correct explanation of A
c) A is true but R is false
d) A is false but R is true